US Navy selects Radiant microreactor for Crane

Radiant has been selected by the US Navy for a proposed installation of its Kaleidos transportable nuclear microreactor at Naval Weapons Station Crane in Indiana. The project is intended to provide an additional source of electricity for critical shore infrastructure, but prototype testing, environmental review, site preparation and regulatory coordination remain necessary before deployment.

Radiant announced the selection on 20 October, linking it to the US military’s Janus programme for evaluating advanced nuclear power at defence installations. The company already has separate microreactor arrangements involving the Army and Air Force. Those programmes represent distinct selections and development activities, rather than proof that the same reactor has entered operational service at all three departments.

Kaleidos is designed as a factory-built, transportable high-temperature gas-cooled reactor producing approximately one megawatt of electrical output. Radiant specifies up to five years between refuelling and a proposed operating life of twenty years. These figures describe the intended design and service model; the company has not provided results from an operating Kaleidos unit at Crane.

A reactor produces thermal energy through controlled nuclear fission. The cooling and power conversion equipment must transfer that heat and convert part of it into electricity usable by the site’s distribution system. The thermal rating of the reactor and its electrical output are different quantities, so the stated one-megawatt figure should not be interpreted as the total heat generated in the core.

Radiant’s design uses gas for reactor cooling rather than a primary system dependent on water. The company says Kaleidos requires no cooling water and is intended to avoid extensive on-site excavation. Its full installation will nevertheless require connections, safety systems, security arrangements and a means of managing the heat rejected by the complete power conversion process.

Manufacturing substantial equipment in a factory could reduce the amount of specialist work needed at each receiving site. That advantage depends on repeatable production, suitable transportation arrangements and the ability to connect the delivered system to local infrastructure without compromising its safety or performance requirements. A transportable design remains a nuclear installation with site-specific obligations.

At Crane, any proposed connection to essential electrical loads will require assessment of the existing network and the characteristics of the reactor’s output. The integration design must account for how electrical demand varies, how equipment responds to faults and how power supply arrangements are managed when the reactor is not available.

Those considerations are separate from the initial selection. The Navy has not disclosed a final grid connection design, identified individual buildings to be supplied or announced an operating date for the installation. The company’s description of energy independence expresses a project objective rather than a verified state of the existing base infrastructure.

Radiant plans to assess Kaleidos through testing at Idaho National Laboratory’s Demonstration of Microreactor Experiments facility, known as DOME. The company identifies full-scale, full-power and extended-duration operation as part of its testing campaign, intended to generate evidence about reactor performance and reliability before wider deployment.

A prototype test programme provides opportunities to examine interactions between the reactor, cooling system, controls and power conversion equipment. Engineers must determine whether operating behaviour remains within the specified limits, including during planned changes in demand and other test conditions. Completion of one test programme does not remove the requirement to satisfy the rules applying to subsequent installations.

The Navy’s project will involve coordination with the Army, Defense Innovation Unit, the Nuclear Regulatory Commission and other participants. Radiant also identifies technical participation by organisations associated with the Naval Nuclear Propulsion Program, whose experience concerns nuclear systems used by the US military. That expertise can support review of the proposed installation, but it is not itself a licence or acceptance certificate for Kaleidos.

Physical protection, environmental requirements and arrangements for handling nuclear materials form part of the overall development programme. The scope of these obligations will depend on the configuration, site and responsible authorities, while approval processes must be completed before operations begin. No final approval for the Crane installation was disclosed with the October announcement.

The longer-term industrial plan involves manufacturing transportable reactors for multiple customers. Producing additional units will depend on qualified suppliers, approved production processes and suitable nuclear fuel arrangements. Radiant has described fuel supply partnerships, although contracted material and manufacturing plans should not be confused with completed commercial reactor deliveries.

Defence installations currently use combinations of grid supply, backup generation and resilience measures suited to their missions. A reactor offering sustained electricity could add another source of supply, with its practical contribution depending on the operating configuration and the site equipment connected to it. Other causes of interruption, including distribution faults and maintenance needs, would still have to be managed.

The selection at Crane is therefore a prospective deployment milestone within a wider reactor development programme. Radiant must complete the required engineering and approval stages before its proposed one-megawatt system can supply naval infrastructure, and neither the purchase price nor a definitive commissioning date has been disclosed.